Shotgun recoil is all about payload weight , velocity and guns weight. With a 8 pound gun:

1oz 1180fps 13.2 ft/lb 1300fps 16.7 ft/lb
1 1/8 1200fps 17.4 ft/lb 1250 19.2 ft/lb
1 1/2 oz at 1330 fps has 39.9 ft/lbs ( 300 mag )

9 double 00 should work on the average person, one would think.